In developing a model for predicting the nonabelian gauge coupling constants we argue for the phenomenological validity of a “principle of multiple point criticality”. This is supplemented with the assumption of an “(grand) anti-unified” gauge group SMGgen. ∼ U(1)gen. ×SU(2)Ngen. ×SU(3)Ngen. that, at the Planck scale, breaks down to the diagonal subgroup. Here Ngen is the number of generations ...

We suggest a simple grand unified theory where the fifth dimensional coordinate is compactified on an S1/(Z2 × Z ′ 2) orbifold. This model is based on the supersymmetric flipped SU(5) × U(1) grand unified theory, which can realize not only the triplet-doublet splitting but also the natural fermion mass hierarchies. The triplet-doublet splitting is realized by S1/(Z2 × Z ′ 2) orbifolding, which ...

There is a unique SU(4) ⊗ SU(2)L ⊗ SU(2)R gauge model which allows quarks and leptons to be unified at the TeV scale. It is already known that the neutrino masses arise radiatively in the model and are naturally light. We study the atmospheric, solar and LSND neutrino anomalies within the framework of this model.

We test the unified-gauge formalism by computing a Wilson loop in Yang-Mills theory to one-loop order. The unified-gauge formalism is characterized by the abritrary, but fixed, four-vector Nμ, which collectively represents the light-cone gauge (N2 = 0), the temporal gauge (N2 > 0), the pure axial gauge (N2 < 0) and the planar gauge (N2 < 0). A novel feature of the calculation is the use of dist...

Gauge unification is widely considered to be a desirable feature for extensions of the standard model. Unfortunately the standard model itself does not exhibit a unification of its running gauge couplings but it is required by grand unified theories as well as the noncommutative version of the standard model [2]. We will consider here the extension of the noncommutative standard model by vector...

The interpretation of the apparent unification of gauge couplings within supersymmetric theories depends on uncertainties induced through heavy particle thresholds. While in standard grand unified theories these effects can be estimated easily, the corresponding calculations are quite complicated in string unified theories and do exist only in models with unbroken E6. We present results for hea...